# The effect of convalescent plasma therapy on the rate of nucleic acid negative conversion in patients with persistent COVID-19 test positivity

## TL;DR

This study found that convalescent plasma therapy does not significantly speed up the clearance of SARS-CoV-2 in patients with prolonged positive test results.

## Contribution

The study provides evidence against the effectiveness of convalescent plasma in accelerating viral clearance for patients with persistent COVID-19 positivity.

## Key findings

- Convalescent plasma therapy did not significantly increase the negative conversion rate on day five, ten, or fifteen post-therapy.
- The hazard ratios for negative conversion were not statistically significant in any of the time points analyzed.
- Findings do not support the hypothesis that convalescent plasma accelerates viral clearance in patients with prolonged positivity.

## Abstract

This study investigates the association between convalescent plasma therapy and the negative conversion rate in patients with persistent COVID-19 test positivity.

A retrospective analysis was conducted on patients with severe or mild to moderate COVID-19 whose viral nucleic acid tests remained positive for over 30 days. Patients were categorized into two groups: those who administered convalescent plasma therapy and those who were not. Data collected included information on therapy strategies used (convalescent plasma, corticosteroids, interferons, etc.), patients’ demographic characteristics, comorbidities, therapeutic medications, and nucleic acid testing results. Patients in the convalescent plasma therapy group were matched 1:2 ratio with those in the non-convalescent plasma therapy group. Cumulative negative conversion rates on the fifth, tenth, and fifteenth days post-therapy initiation were analyzed as dependent variables. Independent variables included therapy strategies, demographic characteristics, comorbidities, and therapeutic medication usage. Univariate analysis was conducted, and factors with a p-value (P) less than 0.2 were included in a paired Cox proportional hazards model.

There was no statistically significant difference in the cumulative negative conversion rate between the convalescent plasma therapy group and the non-convalescent plasma therapy group on the fifth, tenth, and fifteenth days. Specifically, on day the fifth, the negative conversion rate was 41.46% in the convalescent plasma therapy group compared to 34.15% in the non-convalescent plasma therapy group (HR: 1.72, 95% CI: 0.82–3.61, P = 0.15). On the tenth day, it was 63.41% in the convalescent plasma therapy group and 63.41% in the non-convalescent plasma therapy group (HR: 1.25, 95% CI: 0.69∼2.26, P = 0.46). On the fifteenth day, the negative conversion rate was 85.37% in the convalescent plasma therapy group and 75.61% in the non-convalescent plasma therapy group (HR: 1.19, 95% CI: 0.71–1.97, P = 0.51).

Our finding does not support the hypothesis that convalescent plasma therapy could accelerate the time to negative conversion in patients who consistently test positive for COVID-19.